Relay



Nov. 18, 1930. M. SCHLEICHER ET AL Y 1,782,100

RELAY Filed July 13, 1927 2 Sheets-Sheet 1 IvveA To/es I MAA/PREQ SEb/LE/LH/i/ PAL/L DAR/O IBY Mew ATrORA/E Nov. 18, 1930.

M. SCHLEICHER ET AL RELAY Filed July 15, 1927 2 Sheets-Sheet -2 MA /pna-o PAL/'1. C R/a Patented Nov. 18, 1930 UNITED STATES.

PATENT OFFICE MANFRED SCHLEICHER, OF BERLIN-CHARLOTTENBURG, AND PAUL CARIO, F BERLIN- GRUNEWALD, GERMANY, ASSIGNORS TO SIEMENS & HALSKE AKTIENGESELL- SCHAFT, OF SIEME NSSTADT, NEAR, BERLIN, GERMANY, A CORPORATION OF GERMANY RELAY Application filed July 13, 1927, Serial No. 205,307, and in Germany June 24, 1926.

Our invention refers to relays, and more automatically disconnecting defective parts of a line system.

Hitherto the several parts of an electric line system have been supervised by relays Whose time interval for the release grows with growing voltage and diminishes with increasing current. For instance, if the time interval for the release is proportional to the quotient of voltage and current, in other words to the resistance of the faulty circuit, the time interval of release is in the well defined linear relation to the distance from the faulty point.

In the drawings affixed to'this specification and forming part thereof, Figs. 1 and 2 illustrate the characteristics of the systems hitherto used; Fig. 3 illustrates those of the new system according to this invention; and Figs. 4 and 5 show diagrammatically by way of example two forms of a relay embodying our invention.

In Fig. 1 of the drawings, the mode of operation of a line protection as hitherto employed is shown in a graphical manner. On the abscissa axis are plotted the distances between the supervisory stations B,. C, I), E, G,

from the central station A, the several parts of the line system being thus shown in the correct proportion as to length. On the ordinate axis is plotted in seconds the time after which clear-out relays will be actuated whenever a defect occurs at any point of the line AG. The relays may be designed, for instance, in such manner and may be connected to current transformers having such transformation ratio that their time interval of release the abscissa axis are drawn in dashes. With the aid of Fig. 1 the idea underlying the present invention will now be explained.

' For instance, if a short circuit F occurs at a distance of 70 kilometers from the central station A, relay D will cut out after the lapse of one second. In case that the rela or the switch controlled by it should fail, then, after two seconds the relay at'the adjoining station C would effect the disconnection. If this relay also should fail for some reason, or if the switch appertaining to it should fail to disconnect the line, the relay disposed at B would operate after five seconds, or the relay at A after seven seconds. A drawback connected with this arrangement lies in the fact that a defect which occurs near the end of a long line system can be provided for only after a comparatively long intervalof time.

Thus, for instance, a defect occurring at a distance of 48 kilometers from the starting point A would be cut out by the relay arranged at B only after about three seconds. At very great distances of the substations from one another these retardations can assume very undesirable values and it has therefore been suggested to adjust the relays either by varying the numbers of windings of the current transformer or by means of regulating resistances in such manner that they will, disconnect the part of the line system appertaining. to them within a sufiiciently small time interval predetermined for the system as a whole, even if the defect should occur at the extreme end of the respective part of the system.

The time intervals of release in accordance with a system such as just referred to are shown in Fig. 2, where the straight lines representing the time intervals take such a course that at the end of each line section the time interval is equal to one second. As shown in Fig. 2, all straight lines are thus imparted a difierent inclination. Such an arrangement can, however, give rise to faulty conn ections. For instance if a defect occurs at F, the relay mounted at D would elfect a correct disconnection. However, if this relay should fail disconnect-ion would not be effected by the adjoining relay arranged at C, but by the relay disposed at B,

viations from the linear proportion occur,

still greater drawbacks will ensue.

These drawbacks are obviated according to this invention by causing the rate at which the time interval of release grows with the increase of the quotient of voltage and current to remain constant, no matter how that limit of this quotient is adjusted at which the time interval of 'release has the desired low value, or, in other words, even in the case where all the relays are adjusted in such manne'r that they will disconnect a defect near the end of the, respective part of the line system after the lapse of one second, the lines which represent their "time intervals for operation when the defect occurs beyond the section of the line apportioned to them will nevertheless remain parallel, as is' shown in Fig. 3. It is immaterial what the time interval will be if the defect occurs within the part of the line system apportioned to the relay. llt is suflicient if the time interval, for instanceup to about one half second diminishes still further, in order that in the case of. defects occurring a' short distance behind one of the relays this relay will be sure to disconnect sooner than the relay apportioned to the preceding part of p the system, the time interval of which would amount in this case only to a little. more than one 'second. v

According to the present invention, therefore, a maximum time interval for release, say one second may beprescribed for all the sections of the line no matter how long the sectionsmay be or 'to what extent they 'may'difi'er iii length among themselves, but

and likewise the disadvantage of relays operating according to Fig. 2, namely, the danger of faulty disconnections, is obviated.

The adjustabilit-y of the relays can further be provided for, according to this inven- Ijtion, in such manner that the influence of ffvoltage which tends to increase the time in- ;.1 terval, is diminished by an adjustable re- "aiztion which grows with increasing current.

s dependency? can better be explained H'Z-WI lElll'tlI Q'aiICl- OZE some equations. The time interval T of a relay operating according to Fig. 1 corresponds to the equation where C is a constant value, 6 the voltage, and z the current of the faulty circuit. Thus means are provided in the quotient relay which increase the time interval with growing voltage. and 'fur 'ther means Whichdiminish the interval with growing current.

According to this invention, the action of the means influenced by the voltage is opposed by the current, the effect of such current being in direct ratio to its strength, and being adjustable. This adjustable opposing action of the current i will therefore shorten the lag or retardation (time interval) in the release of the relay. In consequence thereof, if a/leak or defect should develop exteriorly of the line section apportioned to a particular relay, the new time interval of release of said relay will be.

The opposing action of the current is adjusted in accordance with the length of the line section to be protected by the relay. This adjustment has no effect Whatever on that increase in the time interval of release of the relay which occurs when a leak or defect occurs in the line at a distance greater than the protective range of the relay. If relays constructed and arranged in accordance with the present'inventio'n are located at the same points or intervals as those indicated at A, B, C, D, and E in Fig. 1, and if such new relays are adjusted in such a manner that each relay will, in the event of a short-circuit in the linesection apportioned to such relay, respond or become effective within the same length of time, for instance, one second, the characteristic lines representing the action of the several relays, will be parallel in those portions which correspond to line sections lying outside of the individual line sections apportioned to the respective relays. This novel result is shown clearly in Fig. 3'.

It will be understood that the time intervals for release of a given relay for defects occurring Within the section of the line apportioned to said relay need not increase according to any definite'mathemati cal relation and may or may not have a constant rate of increase depending upon the distance of the defect from the relay, provided only that the maximum interval is that predetermined tor the section, as, one second. In fact the inertia of the parts, both electrical and mechanical, will complicate the curve release.

Fig. 4 illustrates in a diagrammatic manner and by way of example a relay embodying this invention.

1 is the line system to be protected, 2 is a Ferraris disc, and 3 is a slide. The disc 2 .is acted upon by a driving magnet 4 which is traversed by the current from a current transformer 5 and tends to turn the Ferraris disc in the direction of the arrow. A constant magnet 6 is provided for braking the disc. The saturation of the magnet iron 4 and the braking force are balanced in such manner that the velocity of rotation of the F erraris disc 2 increases in 'a linear manner in proportion to the current in the line system 1. The disc 2 is provided with a pair of contacts 7 serving for closing. the release circuit, as soon as it is carried by the disc 2 into contact with the slide 3. The slide is acted upon by the magnet core 9 against the action of a spring 8. The magnet core 9 is movable within a voltage coil 10, which is supplied with current from the voltage transformer 11. The curve of contact of slide 3 is so shaped that the distance to be travelled by the pair of contacts 7 is proportional to the voltage. Now the voltage coil 10 is further provided with a current winding 12 which is connected in-parallel with the adjustable resistances 13, both being inserted in the circuit of the current transformer 5. As long as the line system is free from defects the Ferraris disc 2 is prevented from rotating by its nose 1 1 abutting against an iron core 15 mounted at one end of a double armed lever 16, the other arm of which carries a magnetcore 17. The core 15 is controlled by a coil traversed by current from the current transformer 5. the coil of the magnet core 17 is connected to the voltage transformerll. The current tends to pull the magnet core 15 out of the way of the nose 14, but is counteracted by the magnet core 17. However, if a short circuit occurs the voltage is diminished and the current increases. and in consequence thereof the current will dominate at the lever 16 and will pull the magnet core 15 outset the way of nose 14, thus allowing the disc to rotate with a velocity which is approximately proportional to the short-circuit current. The voltage coil 10 now allows the spring 8 to act on the slide 3, the more so the more the voltage has dropped and therefore the distance to be travelled by the pair of contacts 7 is diminished in proportion, until the contacts meet the curved portion of the slide 3 and thereby close the releasing circuit. However, the voltage coil 10 is counteracted by the current coil 12, so that the slide 3 is displaced-still further under the influence of spring 8 and the distance to be travelled by the contacts 7 is diminished still further, the more so the greater the short circuit current. The rate of this diminution can be adjusted by means of the regulating resistance 13. If this resistance is cut out altogether,

- the coil 12 is short-circuited and the counterof this current coil and the more the time .interval of release will be diminished. The

current traversing the driving magnet 4 will not be influenced materially by the variation of the regulating resistance 13.

The effect of the short circuit current tending to diminish the time interval of release can also be obtained by mechanical means, as shown for example in Fig. 5. Here the short-circuit current of the line system 21 acts by means of the current transformer 22 and connecting wires 23 and 24 on a bimetal rod 25. Under the influence of the heat generated by the current this rod will bend and in doing so will come in contact with the slide as shown in dash lines. This contact will cause a release circuit (not shown) to be closed, which causes the switches to be opened. In the circuit of the bimetal rod is inserted a choking coil 27, the saturation of which is such that the rate of travel of contact 28 is approximately proportional to the current. v

The position of slide 26 is dependent upon the voltage magnet 29 which is excited by the voltage transformer 30. As long as the current in the line system 21 does not exceed the normal value, the circuit of the bimetal rod 25 is bridged by the connections 31 and contact- As soon, however, as the current increases, the current-magnet 37 will move a lever 33 counter to the action of spring 34 and the nose 35 will then abut against the contact piece 32 and will remove the short circuit. The bimetal rod is now supplied with current and will travel the distance adjusted by the voltage at the rate dependent upon the current. However, this distance is further dependent upon the position of lever 33 upon which rod 25 is mounted. The fulcrum of this lever can be varied by inserting a bolt in any one of a plurality of holes 36 provided for this purpose. The greater the distance between the fulcrum and the bimetal rod 25, the greater the variation of the position of this rod for a predetermined adjustment of the other arm of the lever, and this adjustment is again the greater, the greater the short circuit current, and the more the contact will travel towards the curve 26, and the smaller will be the distance to be travelled until contact is made.

This invention can also be applied without any difliculties to such relays, in which the distance to be travelled by the contact is invariable, while the rate of travelling is directly proportional to the current and inversely proportional to the voltage. Thus 1. A protective relay comprising means for automatically cutting out. part of a line systern after a predetermined time: interval, which interval increases in proportion to an increase of voltage and decreases in proportion to an increase in current, and means for setting said relay to operate after a predetermined time interval, with a predetermined value of the quotient of voltage and current, without affecting the increase of the time interval for the operation of the relay in the event the predetermined value of said quotient should be exceeded.

2. A protective relay comprising means for automatically cutting out part ofa' line system after a predetermined time interval, which interval increases in proportion to an increase of voltage and decreases in proportion to an increase in current, and adjustable means, controlled by the current, for diminishing the influence of the voltage and for setting said relay to operate aftera predetermined time interval, with a predetermined value of the quotient of voltage and current, without afieoting the increase of the time in terval for the operation of the relay in the event the predetermined value of said quotient should be exceeded.

3. A protective relay comprislng'a movable member for automatically cutting out part of a line system after a predetermined time interval, which interval increases in proportion to an increase of voltage anddecreases in proportion to an increase in current, means for moving said movable memher at a rate which grows with the current, voltage-controlled means for limiting the distance traversed by said member, and adjustable additional current-controlled means for making said distance dependent upon the current, and for setting said relay to operate after a predetermined time interval, with a predetermined value of the quotient of voltage and current, without aifecting the increase of the time interval for the operation of the relay in the event the predetermined value of said quotient should be" exceeded.

.4. A protective relay comprising a movable member for automaticallyfbutting out part of a line system after a predetermined time interval, which interval increases in proportion to an increase of voltage and decreases; in proportion to an increase in current, current-controlled means for moving said movable member, means influenced by the voltage for limiting the distance traversed by said member, and adjustable current-controlled means for opposing the influence of the voltage on said last mentioned means, and for setting said relay to operate after a predetermined time interval,

with a predetermined value of the quotient of voltage and current, without affecting the said timing mechanism and operative to increase said time interval; a second, oppositely directed winding associated with sa'id' coil and traversedby a regulatable current corresponding to the current in the faulty I circuit,-and means for adjusting said current for setting said relay to operate after a predetermined time interval, with a predetermined value of the quotient of voltage and current,-without affecting theincrease of the time interval for the operation of the relay in the-event the predetermined value of said quotient shdilld be exceeded.

6. A protective relay comprisinga movable member for automatically cutting out part of a line system after a predetermined time interval, which interval increases in proportion to an increase of voltage and decreases in proportion to an increase in ourrent, ourrent-controlled'rmeans for moving said movable member at a rate which grows with the current, voltage-controlled. means for limiting the distance traversed by said member, adjustable additional current-controlled'means for making said distance: dependent upon the current and for setting said; relay to. operate after a predetermined time interval, with a'predetermined value out affecting the increase of the time inter val for the operation of the relay in the event the predetermined value of said'quo tient should be exceeded, and current-controlled ,mechanism for maintaining said,

movable member in, initial position.

-' 7. A protectlve relay comprising a mov-.

able member for automatically cutting out' I part of a line system after a predetermined time interwal, which] interval increases in proportion to an lncrease of voltage and decreases in proportlon to an increasein current, current-controlled means for moving said movable member. at a'rate whichgrows 115 of the quotient of voltage and current, withwith the current, voltage-controlled means for limiting the distance traversed by said member, and adjustable additional currentcontrolled means for making said distance dependent upon the current, including a double-armed lever, one arm of which determines the initial position of said movable member, a current-controlled magnet adapted to influence the other arm of said lever to move the same, and means for varying the fulcrum of said lever, whereby said relay is set to operate after a predetermined time interval, with a predetermined value of the quotient of voltage and current, without affecting the increase of the time interval for the operation of the relay in the event the predetermined value of said quotient should be exceeded.

8. A protective relay for automatically cutting out a defective part of a line system after a predetermined time interval, and. apportioned to a definite section of said line system, including a pair of contact members, and adjustable mechanism controlled by the line current and voltage and adapted to be set to close said contacts within a predetermined time interval when the quotient of voltage and current has attained a predetermined value corresponding to the length of said apportioned section of the line, said mechanism including voltage-controlled means operative to maintain the rate of increase of said time interval constant when said predetermined Value of the quotient of voltage and current is exceeded, whereby the rate of increase of said time interval for defects occurring beyond said section is independent of the length of said "section.

' In testimony whereof we aflix our signatures.

MANFRED SCHLEICHER. PAUL GARIO 

